Pothos deleonii M. P. Medecilo-Guiang & D. Cabactulan, 2024

Medecilo-Guiang, Maria Melanie P. & Cabactulan, Derek, 2024, Pothos deleonii (Araceae, Potheae, Pothoideae), a new species from Bukidnon, Mindanao, Philippines, PhytoKeys 247, pp. 183-190 : 183-190

Pothos deleonii M. P. Medecilo-Guiang & D. Cabactulan sp. nov.

Figs 1 , 2

Type.

Philippines • Bukidnon Province, Manolo Fortich date: February 18, 2024, MPMG 1005 (holotype PNH! PNH 259023 ); isotypes CMUH!)

Diagnosis.

This new species is morphologically similar to Pothos philippinensis based on vegetative characters but differs by the purplish peduncle, dark wine red to purplish black spathe and pendulous peduncle and acuminate to caudate (vs. acuminate to apiculate) leaf apex. P. deleonii is closest to R. kingii and P. atropurpurascens M. Hotta by having a purple cylindrical spadix but differs from 2 later species by having a much longer, purplish green to dark purple peduncle, 16–18 cm long (vs 5 cm long in P. kingii and 8 cm in P. atropurpurascens ) broadly ovate spathe, subsessile spadix and 7 / 10 the entire length of the spathe, bigger diameter of flowers (2 mm) and flower orientation.

Description.

Plant growth glabrous, root climbing, fibrous liana. Stem moderate slender, slightly woody, terete, green, internodes 2 cm long by 7 mm in diameter in juvenile stage and 7 cm long by 3 mm in diameter upon maturity, younger shoots arising above from the base of the half of the entire length of older stem. Roots present along stem when juvenile, fewer to absent towards the terminal shoots with inflorescence. Leaves spreading, long petiolate, petiole slender angular, 45 degree angled towards the stem, 6–15 cm long by 4–12 mm in diameter, petioles deeply canaliculate with petiolar sheath prominently distinct, erect extending to pulvinus and imbricate to the stem, base decurrent, apex prominently geniculate, petiolar sheath apically ligulate in young growth, ligule and sheath margins later scarious-disintegrating, 7–14 cm long by 0.6–2.5 mm wide, 7 / 8 of the entire length of the petiole. Lamina oblong-lanceolate, occasionally falcate, asymmetrical, coriaceous, margins entire, flattened, shallowly sinuate to slightly conduplicate, 15.5–26.3 cm long by 4–6 cm wide, apex acuminate to caudate and thickened, base acute to obtuse, slightly cordate in juvenile stage, adaxially slightly glossy, dark green and abaxially pale green. Venation closely pinnate, brochidodromous, midrib pale green, adaxially flattened and abaxially rounded raised, primary lateral veins arising running at the base of midrib towards the intra-marginal veins, secondary veins arising at each primary lateral vein, close-spaced disorganized reticulated towards the intra-marginal vein, 2 intra-marginal veins on both sides of the leaf, arising from the base of midrib towards the apex, disorganized reticulated, primary intra-margins 6.5–9.0 mm wide, secondary intra-margins 0.8–1.0 mm wide, venation adaxially less prominent to absent when fresh and slightly present when dry, abaxially prominent visible in both fresh and dry state, intra-marginal veins raised abaxially when dry, outer intramarginal vein remaining very close and parallel to margin. Inflorescence solitary, elongated, deflexed, pendent, and arising from each terminal of matured stem, positive geotropic. Peduncle long terete, stout, deflexed, base purplish-green, dark purple towards the base of the spathe, 16–18 cm long by 2–3 mm in diameter. Spathe broadly ovate, concave to cucullate, apex acuminate, curved, base cordate and slightly decurrent on the peduncle, dark wine red when fresh and purplish black when near wilting, 9.2–10.0 cm long and 4.5–5.5 cm wide, softly-leathery when fresh and papery when dried, prominently 9 - nerved, veins dirty white when fresh and dark purplish black when dried, less prominent acrodomous venation. Spadix long cylindrical, stout, subsessile, dark purplish, 6.4–6.9 cm long by 3.5–4.0 mm in diameter, 7 / 10 the entire length of the spathe, flower c. 2.7 mm, tepals 1 mm by 0.70 mm, oblong-cymbiform, dark purplish-black, apex fornicate, triangular, truncate, minutely 3–4 - lobed, flower compressed angular-ellipsoid, black purplish, stylar region truncate, centrally depressed, 1.5 mm in diameter, stigma prominently punctiform, stamens, 0.3 mm long by 0.1 mm wide, filaments strap-shaped, thecae c. 0.2 mm in diameter, creamy yellow, ovary 1.0– 1.6 mm high by 0.25–0.70 mm in diameter, fertile zone 5.2–5.8 cm long, appendix 8–11 mm long. Infructescence not observed.

Ecology and habitat.

Known only in a highly restricted area in two sites in degraded secondary, open-canopy dipterocarp forest in a 500 - hectare avian conservation site located at the northern foothills of Mt. Kitanglad, 1,150 and 1,270 m a s l. The plant grows from the ground or at the base of trees ( Shorea sp. ) and trunk of Alsophila sp. , 12–20 cm dbh; adherent to host plants from the ground to 4–6 meters, at which plants become branched and grow freely, either pendent or supported by vines or branches of adjacent trees. No specific association with plants other than host plants can be gleaned. But the habitat is favorable to other aroids like Alocasia sanderiana , A. zebrina , and Rhaphidophora sp.

Distribution.

Philippines. BUKIDNON: Manolo Fortich, (exact location withheld as a conservation measure).

Vernacular.

None recorded.

Etymology.

The specific epithet honors Dr. Miguel David De Leon, a vitreoretinal surgeon and wildlife conservationist, who first photographed the species in situ, and supports the conservation of wild flora, particularly orchids and hoyas, and fauna, specifically raptors, in Mindanao.

Uses.

No known usage in traditional medicine; potentially valuable in horticulture.

Conservation status.

Extensive survey in the 500 - hectare area revealed only 12 mature individuals. Because the plants are located in an avian conservation site and constantly monitored by the Robert S. Kennedy Bird Conservancy, there are currently no threats. However, due to its small population and highly restricted extent of occurrence (less than 2 hectares), this species is considered as Critically Endangered based on the criteria of IUCN (2024).

Notes.

P. deleonii belongs to subgenus Allopothos under the Pothos barberianus group and it is closely related to the Philippine endemic P. philippinensis and two Malaysian species: P. kingii and P. atropurpurascens but differs in the size, shape, color and orientation of other floral segments (Table 1 ).

Figures

Figure 1. Pothos deleonii M. P Medecilo-Guiang and D. Cabactulan A habit with flowering branch B leaf apex C leaf base D venation pattern E inflorescence F detail of spadix.

Figure 2. Line drawing of Pothos deleonii A whole plant B leaf phyllotaxy C venation pattern D Inflorescence E detail of spadix: Scale bars: 10 mm (B); 15 mm (D); 5 mm (E).